1. Field of the Invention
This invention relates to a recording and/or reproducing apparatus. More particularly, the present invention relates to a recording and/or reproducing apparatus for a disc-shaped optical recording medium employed as a recording medium.
2. Background of the Invention
In EP-A-047-5595, for example, there has been proposed a disc recording and/or reproducing apparatus in which information signals are adapted for being recorded on or reproduced from a recording disc, such as a magneto-optical disc or an optical disc, employed as a recording medium.
Such disc recording and/or reproducing apparatus includes an outer casing and a disc drive mounted within the outer casing. The disc drive includes a spindle motor, an optical pickup unit, a magnetic head unit and so forth. The disc drive is adapted for recording and reproducing information signals on or from the magneto-optical disc loaded thereon. The disc drive is also adapted for reading information signals from the optical disc loaded thereon.
With the magneto-optical disc, the light beam converged by the optical-pickup unit is radiated on the disc for locally heating its signal recording layer, while a vertical external magnetic field is applied to the signal recording layer of the heated area, for recording information signals conforming to the intensity of the light beam or to the modulation of the intensity of the external magnetic field. Consequently, with this present recording and/or reproducing apparatus, the magnetic head is kept substantially in sliding contact with the magneto-optical disc during the recording mode of recording the information signals on the magneto-optical disc in readiness for driving the optical pickup unit and for enabling the magnetic field of sufficient intensity to be applied by the magnetic head to the signal recording layer.
When reading the information signals from the magneto-optical disc or from the optical disc, the direction of polarization or the intensity of the light beam radiated by the optical pickup unit and reflected by the optical pickup unit is detected. The information signals may be reproduced by demodulating changes in the direction of polarization or in the light intensity. Consequently, when reading the information signals from the recording disc, it is unnecessary for the magnetic head to be in sliding contact with the magneto-optical disc or the optical disc.
With the above-described disc recording and/or reproducing apparatus, it has been proposed to have the magneto-optical disc or the optical disc inserted via an inserting slit formed in the front panel of the outer casing for loading the disc on the disc drive. The disc recording and/or reproducing apparatus of this type is known as the front loading type apparatus and includes a loading unit for transporting the recording disc between the inserting slit and the disc drive. It has been proposed to have the magneto-optical disc or the optical disc housed within a disc cartridge. The disc cartridge is constituted as a thin casing for accommodating the disc therein.
The loading unit of the front loading type disc recording and/or reproducing apparatus, constituted for making use of the disc cartridge, that is the disc cartridge loading unit, includes a cartridge holder into which the disc cartridge is inserted and held therein. The cartridge holder is supported for movement in the outer casing. The cartridge holder is moved towards the disc drive by a disc moving mechanism with the disc cartridge held therein. The cartridge holder transports the disc cartridge up to a position overlying the disc drive for loading the disc cartridge on the disc drive.
Among the above-described disc recording and/or reproducing apparatus, there is such a device in which the magnetic head is kept in sliding contact with the magneto-optical disc when the latter is loaded therein, and in which the magnetic head is spaced apart from the optical disc when the latter is loaded therein.
With the disc recording and/or reproducing apparatus of this type, the disc cartridge is provided with means for deciding whether the recording disc housed therein is a magneto-optical disc or an optical disc, and the magnetic head position is controlled on the basis of the results of decision by the decision means. The decision means detects a discriminating portion formed on the disc cartridge which is in the form of a hole or recess having a different depth for the magneto-optical disc or the optical disc. The mechanism for discriminating the type of the decision means is a manually actuated micro-switch provided on the base block of the disc drive.
However, when the magneto-optical disc is loaded in position in such disc recording and/or reproducing apparatus, the magnetic head is caused to be slidingly contacted with the magneto-optical disc not only when writing the information signals but also when reading the information signals. Consequently, the magnetic head is slidingly contacted with the magneto-optical disc to an unnecessary extent, that is at a higher frequency than the information signal writing frequency, with the result that the wear caused to the magnetic head and to the magneto-optical disc is undesirably increased.
Although it may be contemplated to discriminate whether or not the disc recording and/or reproducing apparatus is in the recording mode and to move the magnetic head based on the results of discrimination, the apparatus tends to be complicated in structure and bulky in size.
When the disc cartridge is loaded on the disc drive of the loading unit for the above-described recording and/or reproducing apparatus by way of loading, the disc cartridge is accommodated and held in the cartridge holder. Consequently, when the disc cartridge is to be removed from the disc drive so as to be discharged out of the disc recording and/or reproducing apparatus by way of unloading, it is necessary to extricate the disc cartridge outwardly from the cartridge holder.
When the unloading is terminated, the cartridge holder is housed within the outer casing of the disc recording and/or reproducing apparatus. Consequently, when the disc cartridge remains accommodated in the cartridge holder, the disc cartridge cannot be taken out of the outer casing.
With the above-mentioned loading unit, the disc cartridge is pushed out during unloading in a forward direction under the bias of a spring mounted within the cartridge holder. With the loading unit, the cartridge holder is introduced into the disc cartridge of the cartridge holder against the bias of the spring, that is as the spring is elastically deformed by the disc cartridge.
Consequently, with the above-described loading unit, smooth insertion of the disc cartridge into the cartridge holder cannot be achieved because of the elastic resistance offered by the spring.
With the loading unit, there is a risk of destruction of the disc cartridge by being thrown into open air under the bias of the spring during unloading. Besides, since the disc cartridge is discharged at a high speed during the unloading operation of the loading unit, there is a risk of destruction of a pawl member used for retaining a shutter member provided in the disc cartridge in a state of closure.